Photovoltaic power generation systems, often referred to as “solar power systems,” are increasing in popularity as a “clean” or “green” energy source, as an alternative to fossil fuels and other energy sources. A photovoltaic power generation system typically includes an array of photovoltaic (PV) cells, referred to as solar cells or solar panels, connected in series and/or in parallel.
A typical solar array install includes groups, or “clusters,” of solar panels are connected in series and then connected to a junction box, called a “combiner box” or simply a “combiner.” Each panel cluster may be connected to the combiner box by a pair of wires referred to as a wire harness. The combiner receives wire harnesses from multiple solar panel clusters and merges these wires into high-gauge wires that carry direct current (DC) from the solar panel clusters to an inverter system and other downstream components of the solar power system. Typically, the individual solar panels in a panel cluster are wired to each other using “pigtails” that are pre-connected to each solar panel (e.g., included during the panel fabrication process), and then return wiring, in the form of one or more wire harnesses, is used to connect the cluster to the combiner box. The wiring pigtail provided on each solar panel may include a pair of wires such that each panel can be connected in series between two other solar panels (or in the case of an end panel, between another solar panel and a wire harness returning to the combine box). The wiring pigtails and return wiring (e.g., wire harnesses) combine to form a wiring circuit connecting a solar panel cluster to the combiner box.
FIG. 1 illustrates one example of a conventional wiring scheme for a cluster in a solar array. In this example, 6 solar panels, labeled P1 through P6, are arranged in a row 20. In this arrangement, the solar panels are arranged in a landscape orientation, i.e., with the longer dimension of the individual panels extending along the direction of the respective panel row. A wiring circuit is arranged to connect the solar panels P1-P6 to a combiner module 50, e.g., a combiner box or other system component or node for combining the wiring of multiple solar panel clusters and/or arrays. In this scheme, wiring circuit 30 includes an inter-module wiring arrangement 32 that connects panels P1-P6 to each other in series, and a return wire harness 34 that connects the inter-module wiring arrangement 32 to the combiner box 50.
The inter-module wiring arrangement 32 of circuit 30 is formed by connecting wiring pigtails 36—typically pre-connected to each solar panel—to each other to connect the solar panels of row 20 to each other in series. Each wiring pigtail 36 may include a pair of pigtail leads 38A and 38B connected to a junction box 35 on the respective solar panel. As shown in FIG. 1, the pigtail lead 38A of one solar panel is connected to pigtail lead 38B of an adjacent solar panel. Return wire harness 34 includes a pair of harness wires 40 coupled to the ends of the inter-module wiring arrangement 32. Thus, return wire harness 34 includes a first harness wire 40A connected to a pigtail lead 38A of panel P1 at one end of the inter-module wiring arrangement 32, and a second harness wire 40B connected to a pigtail lead 38B of panel P6 at the other end of the inter-module wiring arrangement 32.
In this document, a solar panel is “adjacent” to another solar panel only if it is the closest solar panel on either side of the reference solar panel in the same row as the reference panel, regardless of the actual distance between solar panels. Thus, with respect to FIG. 1, panels P2 and P4 are adjacent to panel P3, while panels P1 and P5 are not adjacent panel P3, regardless of the actual distance between any of the respective panels.
FIG. 2 illustrates an example of a conventional wiring scheme for a pair of clusters in a solar array. Essentially, each of the clusters uses the wiring scheme shown in FIG. 1, as described below.
In this example, 12 solar panels, labeled P1 through P12, are arranged in two rows 20A and 20B, with each row including 6 solar panels (row 20A includes panels 1-6, while row 20B includes panels 7-12). The solar panels are arranged in a landscape orientation. A pair of wiring circuits 30A and 30B connect the solar panels P1-P12 to a combiner module 50. Wiring circuit 30A is provided for a first panel cluster (panels P1-P6) and includes an inter-module wiring arrangement 32A that connects the solar panels of row 20A (panels P1-P6) to each other in series, and a return wire harness 34A that connects the inter-module wiring arrangement 32A to the combiner box 50. Similarly, wiring circuit 30B is provided for a second panel cluster (panels P7-P12) includes an inter-module wiring arrangement 32B that connects the solar panels of row 20B (panels P7-P12) to each other in series, and a return wire harness 34B that connects the inter-module wiring arrangement 32B to the combiner box 50.
The inter-module wiring arrangement 32A/32B of each circuit 30A/30B is formed by connecting wiring pigtails 36 to each other to connect the solar panels of the respective row 20A/20B to each other in series. As shown in FIG. 2, the pigtail lead 38A of one solar panel is connected to pigtail lead 38B of an adjacent solar panel. Each return wire harness 34 includes a pair of harness wires 40 coupled to the ends of the respective inter-module wiring arrangement 32A/32B. Thus, return wire harness 34A includes a first harness wire 40A connected to a pigtail lead 38A of panel P1 at one end of the inter-module wiring arrangement 32A, and a second harness wire 40B connected to a pigtail lead 38B of panel P6 at the other end of the inter-module wiring arrangement 32A. Similarly, return wire harness 34B includes a first harness wire 40C connected to a pigtail lead 38A of panel P12 at one end of the inter-module wiring arrangement 32B, and a second harness wire 40D connected to a pigtail lead 38B of panel P7 at the other end of the inter-module wiring arrangement 32B.
As discussed above, in this document, a solar panel is “adjacent” to another solar panel only if it is the closest solar panel on either side of the reference solar panel in the same row as the reference panel, regardless of the actual distance between solar panels. Thus, with respect to FIG. 2, panels P2 and P4 are adjacent to panel P3, while panels P1, P5, and P10 are not adjacent panel P3, regardless of the actual distance between any of the respective panels.
FIG. 3 illustrates another example of a conventional wiring scheme for a pair of clusters in a solar array. As with the example shown in FIG. 2, the panels P1-P12 are arranged in two rows 20A and 20B, with the panels are arranged in a landscape orientation. Again, a pair of wiring circuits 30A and 30B are arranged to connect the solar panels P1-P12 to a combiner box 50. However, unlike in the scheme of FIG. 1, in this scheme each panel cluster includes panels from each row 20A and 20B. A first cluster connected by circuit 30A includes panels P1-P3 of row 20A and panels P10-P12 of row 20B. Thus, the inter-module wiring arrangement 32A of circuit 30A connects panels P1-P3 of row 20A and panels P10-P12 of row 20B. Similarly, a second cluster connected by circuit 30B includes panels P4-P6 of row 20A and panels P7-P9 of row 20B. Thus, inter-module wiring arrangement 32B of circuit 30B connects panels P4-P6 of row 20A and panels P7-P9 of row 20B. Return wire harness 34A includes a first harness wire 40A connected to a pigtail lead 38A of panel P1 at one end of the inter-module wiring arrangement 32A, and a second harness wire 40B connected to a pigtail lead 38B of panel P12 at the other end of the inter-module wiring arrangement 32A. Similarly, return wire harness 34B includes a first harness wire 40C connected to a pigtail lead 38A of panel P4 at one end of the inter-module wiring arrangement 32B, and a second harness wire 40D connected to a pigtail lead 38B of panel P9 at the other end of the inter-module wiring arrangement 32B.
FIG. 4 illustrates another example of a conventional wiring scheme for a single cluster in a solar array. The arrangement shown in FIG. 4 is essentially identical to the arrangement shown in FIG. 1, except the solar panels P1-P6 are arranged in a portrait orientation, i.e., with the longer dimension of the individual panels extending perpendicular to the direction of the respective panel row.
FIG. 5 illustrates an example of a conventional wiring scheme for a pair of clusters in a solar array, wherein the panels are arranged in a portrait orientation. The arrangement shown in FIG. 5 is essentially identical to the arrangement shown in FIG. 3, except the solar panels P1-P12 are arranged in a portrait orientation rather than a landscape orientation.
Each example conventional wiring scheme shown in FIGS. 1-5 includes a number of harness wires 40 to connect one or more panel clusters to a combiner box. It may be advantageous to reduce or minimize the lengths of such harness wires between the panel clusters and combiner box, e.g., to reduce material costs and/or installation time.